By, Steve Barrett
Those who know printing and handle paper know that when the paper grain is wrong, things won’t run smoothly. The grain of the paper is a huge factor in how papers behave when being folded or fed through any type of machine.
To understand paper grain we have to step back into the manufacturing process and learn about how paper is created. We all know paper is a product made from wood, but how it goes from a log to a piece of bright white 20 lb. bond is a bit of a process. The raw wood is ground and mulched into a milky emulsion called pulp. This pulp contains a soup of cellulose fibers that are used to create a single sheet of paper.
The wood fiber is extracted from the liquid elements of the pulp and dried. The way in which the fibers are extracted from the pulp causes the fibers to align together. That parallel arrangement of fibers is what we call grain.
Grain is often referred to as grain-long and grain-short. This is a quick way of saying whether the direction of the grain is aligned with the long dimension of the paper or the short dimension of the paper. Not all papers are equal and some papers have a stronger grain than others. Recycled papers have short fragmented fibers and have a very weak grain.
In folding, it is best to have your fold parallel to the grain of the stock, this helps to ensure that the fold is straight and true, a fold across the grain is more likely to be crooked or jagged. When feeding paper the grain is important because paper will roll more easily perpendicular to the grain.
To find out the direction of the grain of paper you can perform a simple test. Take two sheets of paper and tear them each in half in opposing directions. The tear that is most straight is parallel to the grain of the paper. If the tear wanders off to one side or the other, it’s safe to assume that the tear is going across the grain.